This invention relates to a height adjusting device for a tone arm of a record player, particularly to one easy to handle in adjusting the height of a tone arm and simple to produce.
In using traditional record players, a cartridge fixed at a front end of a tone arm reads information stored in annular shallow grooves on the surface of a record. Different cartridges have different thickness, and if a cartridge is too thin, it cannot reach the surface of a record to pick up music, but if the cartridge is too thick, it has to reach the surface of a record in an inclined condition, impossible to pick up the music precisely. So most conventional record players are provided with a height adjusting device to adjust the height of the cartridge to suit to different thickness of cartridges.
A known conventional record player shown in FIG. 1, includes a tone arm 1, a cartridge (not shown in Figures) is connected to a front end of the tone arm 1, a seat 11 on which a rear end of the tone arm 1 is fixed tightly. A height adjusting device 2 for a tone arm is located under the seat 11, including an outer annular base 20, and an inner annular base 21 threadably engaging an inner wall of the outer annular base 20, as shown in FIG. 2.
The inner annular base 21 has an outer vertical wall 210 provided with threads engaging an inner vertical wall of the outer annular base 20, so that the inner annular base 21 may move up and down relative to the outer annular base 20. Further, the inner annular base 21 has an inner vertical wall 211 threadably engages an outer vertical wall of the seat 11. A vertical rod 110 110 is fixed with the seat 1 at an upper end and also fixed with an annular flat portion of the outer annular base 20, keeping the seat 11 from rotating, but possible to move up and down when the inner annular base 21 is rotated to the left or to the right. Thus, the tone arm 1 fixed tightly on the seat 11 may be lifted up or lowered down if the inner annular base 21 is rotated.
As just described above, the height adjusting device 2 for the tone arm 1 effects its purpose by rotating the inner annular base 21 relative to the seat 11 and the outer annular base 20, and one round rotation of the inner annular base 21 may let the tone arm 1 lifted up only one thread notch. So adjusting speed is very slow, inconvenient to handle in adjusting the height of the tone arm 1. Further, the height adjusting device 2 is not easy to produce, as the outer annular base 20, the inner annular base 21 and the seat 11 are all cut with threads, which are troublesome to form, resulting in high cost and much time necessary in producing.